It was four years ago when Ashton Irwin joined his mates from school to make a band in Australia. His friends -- Luke Hemmings, Calum Hood and Michael Clifford -- had been posting cover videos on YouTube under Luke's channel, hemmo1996. It was time they made it official -- they were 5 Seconds of Summer.

Let's reminisce...

The 5SOS Fam are having a blast passing around old pictures of the guys today in celebration of four years of the band.

Remember when they used to play small shows? I don't!

Their old photo shoots were so ~serious~.

'Don't quit on us yet'.... *clutches heart*

From mirror pics to paparazzi pics

Recreating an old snap

Look at their little faces!

They knew they wanted to be a band all along

From sitting around in a living room to rocking onstage

...Top left pic vvvvv

5SOS fan Nicole made me a tad emotional with this collage

5SOS busking on the street with Myspace hair

Some would argue that they haven't grown up...

The guys themselves are getting all emotional today too

Michael :'(

'Brothers'

Hmmm their costumes over the years:

Happy 4 Years!